In recent years, as an image forming apparatus such as a copier, an apparatus having a numbering function of attaching additional information such as page number to recording paper where a document image is printed has been proposed. As the numbering function, in addition to simple addition of page numbers, a numbering function indicating current page to the total number of document pages, such as (page number)/(total number of pages) (referred to as a “recording of page number with total number of pages”), has been proposed. Japanese Patent Application Laid-Open Nos. 02-106778 and 09-190115 disclose apparatuses to perform the recording of page number with total number of pages.
According to Japanese Patent Application Laid-Open No. 02-106778, to count the total number of document pages, first, a document transfer operation is performed by using an automatic document feeder (ADF) so as to transfer the documents set on a document table, while the number of document pages is incremented upon transfer of each page. The total number of documents as plural pages is counted by repeating the operation until there is no document to be transferred. When the counting of the total number of document pages has been completed, to print the document images on recording paper, the documents, transferred by the ADF at the previous process, are transferred by the ADF again. Upon this transfer, the image forming apparatus reads document images, prints the read images on recording paper, while prints document page numbers and total number of document pages, obtained at the previous process, on the recording paper.
Further, according to Japanese Patent Application Laid-Open No. 09-190115, numbering is performed by using the total number of document pages previously set by a user.
In the apparatus in Japanese Patent Application Laid-Open No. 02-106778, where the total number of document pages is counted in advance by using the ADF, the document transfer operation is performed twice on the same document. That is, (i) the document transfer operation by the ADF for counting the total number of document pages and (ii) the document transfer operation by the ADF for actually printing document images on recording paper are performed. As the documents are transferred with rollers and belt, the incidence of document jam at the ADF may be higher in comparison with other arrangements where the frequency of document transfer is lower. Further, such document jam damages the documents themselves. Further, time for counting the total number of documents is increased in accordance with increase in the number of documents. Further, in an image forming apparatus which lacks an ADF, it may be impossible to count the total number of document pages.
In the apparatus in Japanese Patent Application Laid-Open No. 09-190115, where the number of document pages is inputted by a user in advance, as the counting of the total number of documents is unnecessary, time by the end of printing can be reduced. However, it is necessary for the user to visually check the total number of document pages before execution of image formation. Accordingly, there are possibilities of user's miscount and undesirable image formation by the image forming apparatus due to an erroneous operation by the user's miscount. Further, when the total number of document pages is so large, the user's counting work is heavier in comparison with a case where the total number of document pages is small.